1. Technical Field
The present invention relates to a resonator element, a resonator, an oscillator, an electronic apparatus, a physical quantity sensor, a mobile object, and a frequency adjustment method of a resonator element.
2. Related Art
In the related art, a resonator element using quartz crystal has been known. Such a resonator element has an excellent frequency temperature behavior, and thus, it is broadly used as a reference frequency source or a transmission source of various electronic apparatuses. For example, a method disclosed in JP-A-2003-133879 has been known, as a method of adjusting a frequency of the resonator element.
The frequency adjustment method disclosed in JP-A-2003-133879 is a method of performing the frequency adjustment in a state where the resonator element is accommodated in a package. More specifically, a weight portion (metal film) is provided on both surfaces of a distal end portion of a vibrating arm included in the resonator element. A cover of the package is set so that laser light can penetrate therethrough. The frequency adjustment method is a method of performing the frequency adjustment of the resonator element with the incidence of the laser light to the weight portion through the cover, and removing at least a part of the weight portion provided on both surfaces of the vibrating arm to decrease mass of the vibrating arm. However, such a frequency adjustment method has the following problems.
In the frequency adjustment method disclosed in JP-A-2003-133879, the weight portion (hereinafter, referred to as a “cover side weight portion” for convenience) is provided on the main surface of the vibrating arm on the cover side. Accordingly, the cover side weight portion evaporated by the laser emission is scattered to be attached to the inner surface of the cover. The weight material attached to the inner surface of the cover is evaporated again by the heat of the laser emitted with the deviated emission position through the cover, and the evaporated weight material is scattered to be attached to the cover side weight portion again. As described above, in the frequency adjustment method disclosed in JP-A-2003-133879, reattachment of a part of the removed weight may occur, an adjustable frequency range may be narrowed, and thus, low efficiency and low accuracy of the frequency adjustment are obtained.